The 3MT is fundamentally about science communication and being able to compellingly communicate your research story to a general audience. I forewent this last year to participate in the SSHRC Storyteller's Competition, and which I'll probably try again, this year.
UVic provides a few training sessions in mid/late January:
Very usefully, UVic also provides sample of what the 3MT looks like, by showing the winners from last year's competition.
I texted with my colleague G— as I was filling in my registration earlier today. Here's a link for the form.
I hit "Print" and saved a .pdf version of the filled out form, which needs to be emailed to Ms. Carolyn Swayze at firstname.lastname@example.org. Again, the deadline is this Friday, January 9th!